we also have a 2GM20F. What I did from the start was to put a fuel Primer Bulb like the one at;
http://www.westmarine.com/webapp/wcs/stores/servlet/ProductDisplay?productId=1091554&catalogId=10001&langId=-1&storeId=11151&storeNum=50366&subdeptNum=50406&classNum=50409#.URQ35_LLTSg

in the fuel line after the tank pickup to use to pump the fuel. I STILL have that in line and working very well. I also did purchase a small electric one at an auto parts store in case I needed to use it, but have never installed it.

For MY 2GM it's all I need to use.

Greg